netwerk/dns/HostRecordQueue.cpp

   1 /* vim:set ts=4 sw=2 sts=2 et cin: */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "HostRecordQueue.h"
   7 #include "mozilla/Telemetry.h"
   8 #include "nsQueryObject.h"
   9
  10 namespace mozilla {
  11 namespace net {
  12
  13 void HostRecordQueue::InsertRecord(nsHostRecord* aRec,
  14                                    nsIDNSService::DNSFlags aFlags,
  15                                    const MutexAutoLock& aProofOfLock) {
  16   if (aRec->isInList()) {
  17     MOZ_DIAGNOSTIC_ASSERT(!mEvictionQ.contains(aRec),
  18                           "Already in eviction queue");
  19     MOZ_DIAGNOSTIC_ASSERT(!mHighQ.contains(aRec), "Already in high queue");
  20     MOZ_DIAGNOSTIC_ASSERT(!mMediumQ.contains(aRec), "Already in med queue");
  21     MOZ_DIAGNOSTIC_ASSERT(!mLowQ.contains(aRec), "Already in low queue");
  22     MOZ_DIAGNOSTIC_ASSERT(false, "Already on some other queue?");
  23   }
  24
  25   switch (AddrHostRecord::GetPriority(aFlags)) {
  26     case AddrHostRecord::DNS_PRIORITY_HIGH:
  27       mHighQ.insertBack(aRec);
  28       break;
  29
  30     case AddrHostRecord::DNS_PRIORITY_MEDIUM:
  31       mMediumQ.insertBack(aRec);
  32       break;
  33
  34     case AddrHostRecord::DNS_PRIORITY_LOW:
  35       mLowQ.insertBack(aRec);
  36       break;
  37   }
  38   mPendingCount++;
  39 }
  40
  41 void HostRecordQueue::AddToEvictionQ(
  42     nsHostRecord* aRec, uint32_t aMaxCacheEntries,
  43     nsRefPtrHashtable<nsGenericHashKey<nsHostKey>, nsHostRecord>& aDB,
  44     const MutexAutoLock& aProofOfLock) {
  45   if (aRec->isInList()) {
  46     bool inEvictionQ = mEvictionQ.contains(aRec);
  47     MOZ_DIAGNOSTIC_ASSERT(!inEvictionQ, "Already in eviction queue");
  48     bool inHighQ = mHighQ.contains(aRec);
  49     MOZ_DIAGNOSTIC_ASSERT(!inHighQ, "Already in high queue");
  50     bool inMediumQ = mMediumQ.contains(aRec);
  51     MOZ_DIAGNOSTIC_ASSERT(!inMediumQ, "Already in med queue");
  52     bool inLowQ = mLowQ.contains(aRec);
  53     MOZ_DIAGNOSTIC_ASSERT(!inLowQ, "Already in low queue");
  54     MOZ_DIAGNOSTIC_ASSERT(false, "Already on some other queue?");
  55
  56     // Bug 1678117 - it's not clear why this can happen, but let's fix it
  57     // for release users.
  58     aRec->remove();
  59     if (inEvictionQ) {
  60       MOZ_DIAGNOSTIC_ASSERT(mEvictionQSize > 0);
  61       mEvictionQSize--;
  62     } else if (inHighQ || inMediumQ || inLowQ) {
  63       MOZ_DIAGNOSTIC_ASSERT(mPendingCount > 0);
  64       mPendingCount--;
  65     }
  66   }
  67   mEvictionQ.insertBack(aRec);
  68   if (mEvictionQSize < aMaxCacheEntries) {
  69     mEvictionQSize++;
  70   } else {
  71     // remove first element on mEvictionQ
  72     RefPtr<nsHostRecord> head = mEvictionQ.popFirst();
  73     aDB.Remove(*static_cast<nsHostKey*>(head.get()));
  74
  75     if (!head->negative) {
  76       // record the age of the entry upon eviction.
  77       TimeDuration age = TimeStamp::NowLoRes() - head->mValidStart;
  78       if (aRec->IsAddrRecord()) {
  79         Telemetry::Accumulate(Telemetry::DNS_CLEANUP_AGE,
  80                               static_cast<uint32_t>(age.ToSeconds() / 60));
  81       } else {
  82         Telemetry::Accumulate(Telemetry::DNS_BY_TYPE_CLEANUP_AGE,
  83                               static_cast<uint32_t>(age.ToSeconds() / 60));
  84       }
  85       if (head->CheckExpiration(TimeStamp::Now()) !=
  86           nsHostRecord::EXP_EXPIRED) {
  87         if (aRec->IsAddrRecord()) {
  88           Telemetry::Accumulate(Telemetry::DNS_PREMATURE_EVICTION,
  89                                 static_cast<uint32_t>(age.ToSeconds() / 60));
  90         } else {
  91           Telemetry::Accumulate(Telemetry::DNS_BY_TYPE_PREMATURE_EVICTION,
  92                                 static_cast<uint32_t>(age.ToSeconds() / 60));
  93         }
  94       }
  95     }
  96   }
  97 }
  98
  99 void HostRecordQueue::MaybeRenewHostRecord(nsHostRecord* aRec,
 100                                            const MutexAutoLock& aProofOfLock) {
 101   if (!aRec->isInList()) {
 102     return;
 103   }
 104
 105   bool inEvictionQ = mEvictionQ.contains(aRec);
 106   MOZ_DIAGNOSTIC_ASSERT(inEvictionQ, "Should be in eviction queue");
 107   bool inHighQ = mHighQ.contains(aRec);
 108   MOZ_DIAGNOSTIC_ASSERT(!inHighQ, "Already in high queue");
 109   bool inMediumQ = mMediumQ.contains(aRec);
 110   MOZ_DIAGNOSTIC_ASSERT(!inMediumQ, "Already in med queue");
 111   bool inLowQ = mLowQ.contains(aRec);
 112   MOZ_DIAGNOSTIC_ASSERT(!inLowQ, "Already in low queue");
 113
 114   // we're already on the eviction queue. This is a renewal
 115   aRec->remove();
 116   if (inEvictionQ) {
 117     MOZ_DIAGNOSTIC_ASSERT(mEvictionQSize > 0);
 118     mEvictionQSize--;
 119   } else if (inHighQ || inMediumQ || inLowQ) {
 120     MOZ_DIAGNOSTIC_ASSERT(mPendingCount > 0);
 121     mPendingCount--;
 122   }
 123 }
 124
 125 void HostRecordQueue::FlushEvictionQ(
 126     nsRefPtrHashtable<nsGenericHashKey<nsHostKey>, nsHostRecord>& aDB,
 127     const MutexAutoLock& aProofOfLock) {
 128   mEvictionQSize = 0;
 129
 130   // Clear the evictionQ and remove all its corresponding entries from
 131   // the cache first
 132   if (!mEvictionQ.isEmpty()) {
 133     for (const RefPtr<nsHostRecord>& rec : mEvictionQ) {
 134       rec->Cancel();
 135       aDB.Remove(*static_cast<nsHostKey*>(rec));
 136     }
 137     mEvictionQ.clear();
 138   }
 139 }
 140
 141 void HostRecordQueue::MaybeRemoveFromQ(nsHostRecord* aRec,
 142                                        const MutexAutoLock& aProofOfLock) {
 143   if (!aRec->isInList()) {
 144     return;
 145   }
 146
 147   if (mHighQ.contains(aRec) || mMediumQ.contains(aRec) ||
 148       mLowQ.contains(aRec)) {
 149     mPendingCount--;
 150   } else if (mEvictionQ.contains(aRec)) {
 151     mEvictionQSize--;
 152   } else {
 153     MOZ_ASSERT(false, "record is in other queue");
 154   }
 155
 156   aRec->remove();
 157 }
 158
 159 void HostRecordQueue::MoveToAnotherPendingQ(nsHostRecord* aRec,
 160                                             nsIDNSService::DNSFlags aFlags,
 161                                             const MutexAutoLock& aProofOfLock) {
 162   if (!(mHighQ.contains(aRec) || mMediumQ.contains(aRec) ||
 163         mLowQ.contains(aRec))) {
 164     MOZ_ASSERT(false, "record is not in the pending queue");
 165     return;
 166   }
 167
 168   aRec->remove();
 169   // We just removed from pending queue. Insert record will
 170   // increment this value again.
 171   mPendingCount--;
 172
 173   InsertRecord(aRec, aFlags, aProofOfLock);
 174 }
 175
 176 already_AddRefed<nsHostRecord> HostRecordQueue::Dequeue(
 177     bool aHighQOnly, const MutexAutoLock& aProofOfLock) {
 178   RefPtr<nsHostRecord> rec;
 179   if (!mHighQ.isEmpty()) {
 180     rec = mHighQ.popFirst();
 181   } else if (!mMediumQ.isEmpty() && !aHighQOnly) {
 182     rec = mMediumQ.popFirst();
 183   } else if (!mLowQ.isEmpty() && !aHighQOnly) {
 184     rec = mLowQ.popFirst();
 185   }
 186
 187   if (rec) {
 188     mPendingCount--;
 189   }
 190
 191   return rec.forget();
 192 }
 193
 194 void HostRecordQueue::ClearAll(
 195     const std::function<void(nsHostRecord*)>& aCallback,
 196     const MutexAutoLock& aProofOfLock) {
 197   mPendingCount = 0;
 198
 199   auto clearPendingQ = [&](LinkedList<RefPtr<nsHostRecord>>& aPendingQ) {
 200     if (aPendingQ.isEmpty()) {
 201       return;
 202     }
 203
 204     // loop through pending queue, erroring out pending lookups.
 205     for (const RefPtr<nsHostRecord>& rec : aPendingQ) {
 206       rec->Cancel();
 207       aCallback(rec);
 208     }
 209     aPendingQ.clear();
 210   };
 211
 212   clearPendingQ(mHighQ);
 213   clearPendingQ(mMediumQ);
 214   clearPendingQ(mLowQ);
 215
 216   mEvictionQSize = 0;
 217   if (!mEvictionQ.isEmpty()) {
 218     for (const RefPtr<nsHostRecord>& rec : mEvictionQ) {
 219       rec->Cancel();
 220     }
 221   }
 222
 223   mEvictionQ.clear();
 224 }
 225
 226 }  // namespace net
 227 }  // namespace mozilla